HEADWATERS OF THE PARAGUAY 119 



and which in all probability never would have had a con- 

 cealing value in any "environmental complex" in which 

 the species as a whole lived during its ancestral develop- 

 ment. Indeed, it seems astonishing, when one observes 

 these big beasts— and big waders and other water-birds— 

 in their native surroundings, to find how utterly non- 

 harmful their often strikingly revealing coloration is. 

 Evidently the various other survival factors, such as habit, 

 and in many cases cover, etc., are of such overmastering 

 importance that the coloration is generally of no con- 

 sequence whatever, one way or the other, and is only very 

 rarely a factor of any serious weight. 



The junction of the Sao Lourenpo and the Paraguay is 

 a day's journey above Corumba. From Corumba there is 

 a regular service by shallow steamers to Cuyaba, at the 

 head of one fork, and to Sao Luis de Caceres, at the head 

 of the other. The steamers are not powerful and the voy- 

 age to each little city takes a week. There are other forks 

 that are navigable. Above Cuyaba and Caceres launches 

 go up-stream for several days' journey, except during the 

 dryest parts of the season. North of this marshy plain 

 lies the highland, the Plan Alto, where the nights are cool 

 and the climate healthy. But I wish emphatically to record 

 my view that these marshy plains, although hot, are also 

 healthy; and, moreover, the mosquitoes, in most places, 

 are not in sufficient numbers to be a serious pest, although 

 of course there must be nets for protection against them at 

 night. The country is excellently suited for settlement, 

 and offers a remarkable field for cattle-growing. More- 

 over, it is a paradise for water-birds and for many other 

 kinds of birds, and for many mammals. It is literally an 



